1. Field of the Invention
This invention relates to a sectored distributor for a turbomachine such as a turbojet or a turboprop engine.
A turbomachine comprises turbine stages each comprising a rotor impeller and a distributor, each distributor being sectored, i.e. formed of several distributor segments arranged circumferentially end-to-end.
Each distributor segment comprises two coaxial annular platforms extending inside one another and connected together by substantially radial blades. The outer platform comprises means for fastening on an outer casing of the turbine. The inner platform is integral with a substantially radial annular partition which carries members made of abradable material, located radially inside the inner platform of the distributor. The members made of abradable material engage with annular lips carried by the rotor of the turbine in order to form seals of the labyrinth type.
In the event of substantial wear of the members made of abradable material, it is necessary to replace them with new ones during maintenance operation. With the current art, these members are fixed by brazing on the annular partition of the inner platform of the distributor. The replacing of the members made of abradable material requires a complete dismounting of the segments of the distributor, a machining of each distributor segment in order to remove the worn abradable members, and the brazing of new abradable members on the annular partition. It is then necessary to deposit an antioxidant protective coating on each distributor segment. This operation of replacing abradable members of a distributor is therefore long and expensive.
Moreover, the distributor segments are separated from each other with low play in the circumferential direction in order to authorise thermal dilatations of their platforms during operation. They are in addition subjected during operation to vibrations and relatively substantial dynamic stress which can result in static movements and deformations of these segments.
2. Description of the Related Art
It has already been proposed to rigidify the distributor using means for axial bearing formed on the inner platform segments of the distributor, the means for bearing of a platform sector being intended to engage with corresponding means formed on adjacent inner platform segments in order to limit the deformations of the distributor during operation.
With the current technique, these means for bearing comprise a very hard material called “stellite” which is deposited via a method of laser welding (“stelliting”) which is long, expensive, difficult to implement, and which risks deteriorating the distributor segments. This technology is furthermore not able to be carried out on certain distributors of which the platforms have forms that are too complex (called 3D platforms).